The present invention relates to an optically writeable spatial light modulator of the ferroelectric liquid crystal type and also relates to a driving method thereof, which device and driving method may be utilized in an image processing device, an optical information processing device, or a related device.
Conventionally, a spatial light modulator of the ferroelectric liquid crystal type is utilized as an optical device for modulating the intensity of image information input thereto on a real time basis to output a modulated result. Further, in Japanese Patent Application No. 239594/1990, the inventors have disclosed a method for driving the above noted optical modulator to produce an output image having a continuous gradation.
For a conventional spatial light modulator of the ferroelectric liquid crystal type and its conventional driving methods, there is only one threshold value per writing light intensity level. For example, when there is digital logic using one output light (reading light) in response to two input lights (writing lights), although AND or OR logic functions could be obtained by setting the input light intensity to the threshold value, XOR or XNOR logic function can not be obtained. Also, the connection of several devices in a cascade and synchronizing of the devices is required. This has prevented the conventional spatial light modulator and its conventional driving methods from being applied in optical computing and related areas. Also, according to analog Fourier optical information processing system, because of zeroth order light processing and the dynamic range, the conventional spatial light modulator and its driving methods could not be utilized for the higher-order region.